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  1. #1

    Default Engine Cuts Out at High Speeds - Sometimes (1990 PCM 351)

    Hello All,

    Took the boat out for the first time on Monday after making the folllowing repairs/maintenance for the season:

    - New Fuel Pump and Line
    - New Starter Motor
    - Installed Sea Strainer and Ball Valve
    - Converted from 20w to DexMerc Trans Fluid (changed 3x)
    - Replaced Worn Hoses
    - Oil/plugs/coolant/impeller/battery charge
    - Mostly new fuel (rest had adequate stabilizer)

    I'm running the original PCM 351 (1990 Sunsport) with the standard distributor (no more protec). It ran well all last season and ran beautifully on Monday with the new fuel pump, until...

    We were out about 2 hours running at various speeds (anchored, idle, slow, almost full throttle). Saw a storm approaching, so took cover under a bridge while it passed. By "took cover" I mean we putted around between idle, low speed forward, and low speed reverse for about an hour. Once the storm passed, we decided to head home because more rain was predicted. But now, everytime I tried to go faster than a very low speed, the engine cut out. We were able to get home (about 15 minutes) at very low speed. Kept trying intermittently to increase speed a bit but every time the engine would cut out. Today I ran the engine in my driveway (with garden hose connected). Running nicely now. Let engine warm up, and still running nicely.

    Any thoughts on what this could be and how I could test it so we dont end up getting stuck out on the water? Again to summarize: Engine was running great, putted around for an hour between idle and low speed, then engine would cut out every time we tried to go above a low speed, runs fine in the driveway today.

    Much thanks!


  2. #2

    Default Re: Engine Cuts Out at High Speeds - Sometimes (1990 PCM 351)

    ...also replaced oil and fuel filters before running

  3. #3

    Default Re: Engine Cuts Out at High Speeds - Sometimes (1990 PCM 351)

    I've seen this symptom the result of crud in the fuel tank clogging the pickup tube coarse screen and starving the fuel system. Result is that engine cannot get much past idle rpms. When the engine is shut down, the crud may (not always) clear away from the pick up tube only to get picked up again in what appears random occurrence. It may be a pain depending on the fuel tank access, but best way to correct is to siphon all the fuel out of the tank. The fuel level sender can be removed to get a better view inside and clean out the crude. Also, remove the fuel pickup tube and clean the coarse screen. Good idea to also replace the fuel filter. If you want to reuse the drained fuel, be sure to run it through a filter before putting it back in the tank.

    Even with fuel stabilizer, crud can form if any moisture gets in tank. Moisture can get into the tank when storing with partially empty fuel tank over the winter and the tank breaths with temperature changes. It may take a few seasons for the crud to grow (yes its organic) to the point that it causes problems. There are enzyme fuel treatments that claim to help prevent or fix this crud, but I can't attest to their efficacy. Good luck.

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